Crank pin truing device



. LINDSTROM CRANK PIN TRUING DEVICE Aug. 6, 1935.

Filed Oct Patented Aug. 6, 1935 'y UNrrl-:D STATES PATENT OFFICE 2,010,638 CRANK PIN TRUING DEVICEl Carl R.. Lindstrom, Peru, Nebr.

Application October 10, 1934, Serial No. 747,806

47Claims. (Cl. 51--204) This invention relates to improvements in methods and means for grinding or truing worn crank pins of crank shafts for internal combustion engines and the like, its particular object being to provide a simple instrumentality by means of which the crank pins may be treated without removal from the motor.

In carrying out the invention, the appliance is substantially the exact form of a connecting rod, excepting for thefact that the crank pin bearing of the appliance is supplied with an abrasive or grinding surface, so that said appliance may be substituted in the place of a connecting rod of the motor for the purpose of performing the grinding operation. In this way, the particular crank pin treated is not only ground to a true round, but more importantly it is trued with respect to the cylinder bore alignment.

It will be obvious that in this manner I make the process of performing this delicate operation both simple and economical, save time and expense by virtue of treatment of the crank shaft Without removal from the motor, with results, so far as accuracy is concerned, which no other method in use will accomplish.

With these and other objects in view, the invent-ion consists in certain novel features of construction and combinations and arrangements of parts as will be more fully hereinafter described and pointed out in the appended claims.

In the accompanying drawing, Fig. l is a side elevation of an appliance constructed in accordance with this invention; Fig. 2 is a horizontal sectional view showing the grinding or polishing face of the bearing cap forming a part of the appliance; and Fig. 3 is a diagrammatic view of a motor construction showing the application of this invention in operative position therein.

Referring to the drawing, l designates the body portion of the tool which, Yas hereinbefore premised, has the form and construction of a connecting rod of the motor on which it is to be used. This appliance is provided at one end with a wrist pin bearing 2 and at its other end with a crank pin bearing 3 which is in two sections preferably as is the corresponding bearing of a connecting rod. 'I'he cap section 4 of the crank pin bearing is connected to the complemental section by means of bolts 5 and each of these sections is provided with a removable grinding or polishing segment 3', 4'. These segments may have le-like surfaces or may embody a removable abrasive element as desired. The grinding surface of these sections may be of variousdegrees of roughness and may be made of afford the proper grinding effect.

different materials such as nichrome steel, carbon steel, nickel steel or any substances possessing the necessary abrasive properties.

In using the toolset forth, the connecting rod of the motor is removed and in its place this appliance is positioned, the crank pin bearing being attached with suitable shims 6 interposed so as to The wrist pin bearing end of the appliance is also connected to the piston in the usual manner prior to the in-` sertion of the piston in its cylinder and the connection of the member l to the crank pin. When adjusted in this manner, the crank shaft is then rotatedslowly until the pin is properly trued, the necessary adjustments being made with reference to the cap member 4' so as to finally produce the Y necessary round configuration. y

The application of the invention as aforesaid and the method of carrying out the truing operation is specifically shown in Fig. 3 of the drawing wherein A designates the conventional motor block of an internal combustion motor engine having one or more cylinders B in which reciprocate the usual piston or pistons C. The truing appliance I connects this piston to the crankshaft D in the manner above described and the truing operation is produced by means of the rotation of the crankshaft through the hand crank E or the customary engine starter F which is operated by the battery G of the car or any other suitable source of electric motive power. The carrying out of the method of operation of my invention does not necessitate the removal of the engine head but this portion of the motor is omitted from Fig. 3 for the sake of simplicity of disclosure of my method of procedure.

The great advantage of this method is that a plurality or all of the crank pins may be treated at one and the same time, always with the assurance that they will be properly trued to the bores of the respective cylinders of the motor. Since the pressure applied in the rotation of the shaft is uniform, the operation of truing its crank pins is greatly facilitated and may be carried out by unskilled labor without removal of the crank shaft from the motor or disturbance of the main bearings for said shaft.

I claim:

1. An appliance for truing worn crank pins of shafts of motors comprising a body of the form and construction of a connecting rod of the motor, said body including a wrist pin bearing at one end and a crank shaft bearing at its other end, said last-named bearing having a grinding surface engageable about the crankrpln.

2. The method of truing worn crank pins of shafts of motors which comprises the steps of connecting a piston With the crank shaft by means of a grinding appliance, and rotating the crank shaft to cause the grinding surface to operate upon the crank pin.

3. The combination with a motor block, and its piston, of means for connecting the piston and crank shaft in the place of one of its connecting, rods, said connecting means including means for truing the crank pin of said shaft upon rotation thereof and means for operating the crankshaft to effect the truing operation.

4. The combination with a motor block, and its piston, of an appliance for truing crank pins of the crankshaft, said device having the form of a connecting rod and being adapted to be connected to a piston and crank pin in the place of said rod, said appliance being operative upon rotation of the shaft to perform its truing operation on the crank pin and means for operating the crank 10 shaft to eiect the truing operation.

' CARL R. LINDSTROM. 

